JP2005252691A - Crystal oscillator for surface mounting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface mounted crystal oscillator in which a frequency is prevented from being changed by generated heat of an IC chip. <P>SOLUTION: In the surface mounted crystal oscillator provided with a recessed container having a step part at both edge sides of an inner wall and a piece of quartz crystal with the outer circumference of one edge extending part of an extraction electrode held at the step part of at least one edge side between the step sides, a hollow is provided in the inner wall below the step part of at least the other end side between the step parts, the hollow expands at the both edge sides including the other edge side of the container main body, and the piece of quartz crystal holds the both edge sides. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface mount crystal oscillator (hereinafter referred to as a surface mount oscillator), and more particularly to a surface mount oscillator that prevents frequency change due to heat generation of an IC chip.

(Background of the Invention) Since surface-mounted oscillators are small and light, they are used as frequency and time reference sources, particularly in portable electronic devices. In recent years, the frequency deviation standard has become stricter as the miniaturization further progresses, and one factor that hinders this is the heat generation of the IC chip 2.

(Example of Prior Art) FIG. 4 (ab) is a diagram for explaining one conventional example. FIG. 4 (a) is a sectional view of a surface mount oscillator and FIG. 4 (b) is a plan view of a crystal piece.

  The surface mount oscillator accommodates an IC chip 2 and a crystal piece 3 in a container body 1 and covers a cover 4 so as to be hermetically sealed. The container body 1 is made of a laminated ceramic in which a bottom wall 5 and a frame wall 6 are laminated to form a concave shape. The frame wall 6 is composed of first and second frame wall layers 6 (ab), and step portions are formed on both end sides of the inner wall. The IC chip 2 integrates an oscillation circuit (not shown) and is fixed to the bottom surface of the concave portion by, for example, ultrasonic thermocompression using a bump.

  The crystal piece 3 has excitation electrodes 7 on both main surfaces, and for example, extraction electrodes 8 extend on both sides of one end. Then, both sides of one end portion of the crystal piece 3 are held (adhered) to the step portion on one end side of the container body 1 by the conductive adhesive 9 or the like. The cover 4 is seam-welded, for example, to a metal ring provided on the upper surface of the frame wall of the container body 1.

  The other end portion of the crystal piece 3 is placed on the step portion on the other end side of the container body 1. For example, in the case of a convex shape, contact between the main surface and the inner bottom surface of the crystal piece 3 is prevented, or the application work of the conductive adhesive 9 is facilitated. Further, it is necessary when both ends of the crystal piece 3 are fixed.

(Problem of the prior art) However, in the surface mount oscillator having the above-described configuration, as the miniaturization progresses, the internal volume of the container body 1 also decreases. Therefore, there is a problem that the internal temperature rises due to heat generation of the IC chip 2 and the oscillation frequency changes due to the frequency temperature characteristics of the crystal resonator.

  Specifically, as shown in FIG. 5, the frequency temperature characteristics of a crystal resonator, for example, an AT cut, have a maximum value on the low temperature side and a minimum value on the high temperature side with an inflection point near room temperature (25 ° C.). It has a cubic curve. Usually, the oscillation frequency at normal temperature is set as the nominal frequency.

  However, when the internal temperature rises due to the heat generated by the IC chip 2, the oscillation frequency at room temperature decreases. Therefore, there is a problem that the deviation of the nominal frequency becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface mount oscillator that prevents frequency changes due to heat generation of an IC chip.

  According to the present invention, as shown in the claims (Claim 1), a concave container body having steps on both ends of the inner wall, and an extraction electrode on at least one end of the steps In the quartz resonator for surface mounting provided with a crystal piece on which the outer periphery of the extended one end is held, a configuration in which a recess is provided on an inner wall below the step on the other end of the step And

  With this configuration, the inner volume of the concave container body is increased to increase the heat capacity. Therefore, the temperature rise is suppressed to prevent the oscillation frequency from changing.

  According to a second aspect of the present invention, the crystal piece according to the first aspect of the present invention is the crystal piece according to the first aspect, wherein an extraction electrode extends on both sides of one end portion and is held on the step portion on the one end side. The recess is provided in an inner wall below the step at the other end. As a result, since no depression is provided in the step portion on one end side where the crystal piece is held, the strength is maintained, and the inner volume of the container body can be increased by the depression provided on the other end side.

  According to the third aspect of the present invention, the crystal piece according to the first aspect has an extraction electrode extending on both sides of one end portion and held by the step portion on the one end side, and the recess is provided on an inner wall below the step portion on both end sides. It is done. Thereby, the internal volume of a container main body can be enlarged further.

  According to the fourth aspect of the present invention, the crystal piece according to the first aspect has an extraction electrode extending at both end portions thereof and held by the step portions on both end sides, and the depression is an inner wall that is below the step portion on one end side or both end sides. Is provided. Thereby, even when both ends of the crystal piece are held, the internal volume can be increased.

  FIG. 1 is a cross-sectional view of a surface mount oscillator for explaining an embodiment of the present invention. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.

  As described above, the surface-mount oscillator is formed by fixing the IC chip 2 to the bottom surface of the concave portion of the container main body 1 and holding both ends of the crystal piece 3 from which the extraction electrode extends to the step portion of the inner wall. And here, the hollow 10 is provided under the step part of the other end side among the step parts of the both end side. Specifically, the frame wall 6 laminated on the bottom wall of the container body 1 is formed from the first, second and third frame wall layers 6 (abc). And the 2nd frame wall layer 10b is protruded inward, and the hollow 10 is formed under the step part of the other end side.

  If it is such a structure, the internal volume of the container main body 1 can be enlarged by the hollow 10 provided under the step part of the other end side. Therefore, the heat capacity of the IC chip 2 can be absorbed by increasing the heat capacity in the container body. Thereby, the frequency change by heat_generation | fever is prevented and the frequency deviation (nominal frequency) especially in normal temperature can be maintained within a regulation value.

(Other matters) In the above embodiment, the depression 10 is provided only on the other end side of the container main body 1. However, as shown in FIG. You may provide the hollow 10 below. In this case, since the internal volume of the container body 1 further increases, the heat capacity also increases. However, since the strength of the stepped portion that holds the crystal piece 3 is lowered, it is determined from the relationship between the heat capacity and the strength.

  Further, the crystal piece 3 extends the extraction electrode 8 to both sides of one end and holds it on the step on one end. However, the extraction electrode 8 extends to both ends and the step on both ends as shown in FIG. May be retained. In FIG. 3, the depressions 1 are provided on both ends of the container body 1, but only one end may be provided as described above.

It is sectional drawing of the surface mount oscillator explaining one Example of this invention. It is sectional drawing of the surface mount oscillator explaining the other Example of this invention. It is sectional drawing of the surface mount oscillator explaining the further another Example of this invention. It is a figure explaining a prior art example, the figure (a) is a sectional view of a surface mount oscillator, and the figure (b) is a top view of a crystal piece. It is a frequency-temperature characteristic view of a crystal resonator (surface mount oscillator) for explaining a conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 IC chip, 3 Crystal piece, 4 Cover, 5 Bottom wall, 6 Frame wall, 7 Excitation electrode, 8 Lead electrode, 9 Conductive adhesive agent, 10 Indentation.

Claims (4)

  A surface mount provided with a concave container body having stepped portions on both end sides of the inner wall, and a crystal piece on which at least one end of the stepped portion holds an outer periphery of one end extended from an extraction electrode A crystal oscillator for surface mounting, wherein a recess is provided in an inner wall below a step portion on at least the other end side of the step portion.   2. The crystal oscillator according to claim 1, wherein an extraction electrode extends on both sides of one end of the crystal piece and is held by a step on the one end side, and the depression is provided on an inner wall below the step on the other end.   2. The crystal oscillator according to claim 1, wherein an extraction electrode extends on both sides of one end portion of the crystal piece and is held by a step portion on the one end side, and the depression is provided on an inner wall below the step portion on both end sides.   2. The crystal oscillator according to claim 1, wherein the crystal piece has an extraction electrode extending at both ends thereof and is held by the step portions on both end sides, and the recess is provided on an inner wall below the step portion on one end side or both end sides. .

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